Open or damaged wiring in the brake booster motor position sensor circuit; Failed brake booster motor position sensor; Corroded or loose electrical connectors at the sensor or control module; Faulty brake booster motor assembly; Water or debris intrusion into the sensor or connector; Internal failure in the brake control module affecting sensor readings

DTC codes / C05xx · Brakes, steering and suspension / C058B

C058BBrake Booster Motor B Position Sensor Circuit/Open

Q: What does code C058B mean?

Brake Booster Motor B Position Sensor Circuit/Open. The C058B code indicates that the brake booster motor's position sensor circuit is open or has a fault, meaning the control module cannot detect the motor's position. The computer sets this code when the signal from the sensor is missing or out of range, which can affect brake assist performance.

The C058B code indicates that the brake booster motor's position sensor circuit is open or has a fault, meaning the control module cannot detect the motor's position. The computer sets this code when the signal from the sensor is missing or out of range, which can affect brake assist performance.

SystemChassis

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaBrakes, steering and suspension

Symptoms you may notice

Illumination of the brake system warning light or ABS light on the dashboard
Reduced brake assist, requiring more pedal effort to stop the vehicle
A soft or spongy brake pedal feel
Unusual noises from the brake booster area, such as clicking or whirring
Often no symptoms besides the warning light, especially in early stages

Common causes, most likely first

Open or damaged wiring in the brake booster motor position sensor circuit
Failed brake booster motor position sensor
Corroded or loose electrical connectors at the sensor or control module
Faulty brake booster motor assembly
Water or debris intrusion into the sensor or connector
Internal failure in the brake control module affecting sensor readings

How to diagnose and fix it

Inspect the brake booster motor position sensor connector and wiring for damage, corrosion, or looseness
Check for continuity and resistance in the sensor circuit using a multimeter, comparing to manufacturer specifications
Test the position sensor signal with a scan tool to see if it changes smoothly through the motor's range
If the sensor is faulty, replace the brake booster motor position sensor or the entire motor assembly as required
Repair any open or shorted wires in the circuit, including cleaning or replacing connectors
Clear the code and perform a road test to verify the repair and ensure the code does not return

What Most Techs Overlook on C058B

A common misdiagnosis is replacing the brake booster motor when the actual fault is a chafed wire in the harness near the pedal assembly or firewall.
The position sensor may test fine with a multimeter but still drop out intermittently due to heat or vibration, so a wiggle test while monitoring live data is essential.
This code can be set by a low battery or charging system issue that causes voltage spikes, so always check battery health and grounds before condemning components.
On some vehicles, the brake booster motor position sensor is not sold separately, forcing replacement of the entire booster assembly, which is a costly mistake if the real issue is wiring.
The code may appear after brake system work if the sensor connector is not fully seated or the battery was disconnected during repairs, so verify recent service history.

Can I keep driving with C058B?

If the brake pedal feels normal and the warning light is the only symptom, you can drive cautiously to a repair shop, but avoid heavy braking or towing. If brake assist is noticeably reduced or the pedal is soft, stop driving and have the vehicle towed to prevent an accident.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.